The human skeleton performs six major functions; support, movement, protection, production of blood cells , storage of minerals, and endocrine regulation.

The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull , dentition , long bones , and pelvis exist.

In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. The human female pelvis is also different from that of males in order to facilitate childbirth.

The axial skeleton 80 bones is formed by the vertebral column 32—34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length , a part of the rib cage 12 pairs of ribs and the sternum , and the skull 22 bones and 7 associated bones.

The upright posture of humans is maintained by the axial skeleton, which transmits the weight from the head, the trunk, and the upper extremities down to the lower extremities at the hip joints.

The bones of the spine are supported by many ligaments. The erector spinae muscles are also supporting and are useful for balance.

The appendicular skeleton bones is formed by the pectoral girdles, the upper limbs, the pelvic girdle or pelvis, and the lower limbs. Their functions are to make locomotion possible and to protect the major organs of digestion, excretion and reproduction.

The skeleton serves six major functions: The skeleton provides the framework which supports the body and maintains its shape. The pelvis, associated ligaments and muscles provide a floor for the pelvic structures.

Without the rib cages , costal cartilages , and intercostal muscles , the lungs would collapse. The joints between bones allow movement, some allowing a wider range of movement than others, e.

Movement is powered by skeletal muscles , which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system.

It is believed that the reduction of human bone density in prehistoric times reduced the agility and dexterity of human movement.

Shifting from hunting to agriculture has caused human bone density to reduce significantly. The skeleton helps to protect our many vital internal organs from being damaged.

The skeleton is the site of haematopoiesis , the development of blood cells that takes place in the bone marrow. In children, haematopoiesis occurs primarily in the marrow of the long bones such as the femur and tibia.

In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum. The bone matrix can store calcium and is involved in calcium metabolism , and bone marrow can store iron in ferritin and is involved in iron metabolism.

Hydroxyapatite is in turn composed of Chondroitin sulfate is a sugar made up primarily of oxygen and carbon. Bone cells release a hormone called osteocalcin , which contributes to the regulation of blood sugar glucose and fat deposition.

Osteocalcin increases both the insulin secretion and sensitivity, in addition to boosting the number of insulin-producing cells and reducing stores of fat.

Anatomical differences between human males and females are highly pronounced in some soft tissue areas, but tend to be limited in the skeleton.

The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull , dentition , long bones , and pelvis are exhibited across human populations.

It is not known whether or to what extent those differences are genetic or environmental. A variety of gross morphological traits of the human skull demonstrate sexual dimorphism, such as the median nuchal line , mastoid processes , supraorbital margin , supraorbital ridge , and the chin.

Human inter-sex dental dimorphism centers on the canine teeth , but it is not nearly as pronounced as in the other great apes. Long bones are generally larger in males than in females within a given population.

Muscle attachment sites on long bones are often more robust in males than in females, reflecting a difference in overall muscle mass and development between sexes.

Sexual dimorphism in the long bones is commonly characterized by morphometric or gross morphological analyses. The human pelvis exhibits greater sexual dimorphism than other bones, specifically in the size and shape of the pelvic cavity , ilia , greater sciatic notches, and the sub-pubic angle.

There are many classified skeletal disorders. One of the most common is osteoporosis. Also common is scoliosis , a side-to-side curve in the back or spine, often creating a pronounced "C" or "S" shape when viewed on an x-ray of the spine.

This condition is most apparent during adolescence, and is most common with females. Arthritis is a disorder of the joints. It involves inflammation of one or more joints.

When affected by arthritis, the joint or joints affected may be painful to move, may move in unusual directions or may be immobile completely.

The symptoms of arthritis will vary differently between types of arthritis. The most common form of arthritis: Osteoarthritis can affect both the larger and smaller joints of the human skeleton.

The cartilage in the affected joints will degrade, soften and wear away. This decreases the mobility of the joints and decreases the space between bones where cartilage should be.

Osteoporosis is a disease of bone where there is reduced bone mineral density , increasing the likelihood of fractures.

Osteoporosis treatment includes advice to stop smoking, decrease alcohol consumption, exercise regularly, and have a healthy diet. Calcium supplements may also be advised, as may Vitamin D.